TY - JOUR
T1 - Current extinction rates of reptiles and amphibians
JF - Proceedings of the National Academy of Sciences
JO - Proc Natl Acad Sci USA
SP - 13003
LP - 13008
DO - 10.1073/pnas.1508681112
VL - 112
IS - 42
AU - Alroy, John
Y1 - 2015/10/20
UR - http://www.pnas.org/content/112/42/13003.abstract
N2 - It is hard to know how many species have gone extinct so far because it is difficult to prove that something not seen recently is really gone forever. This paper uses a new, highly conservative statistical method to infer the number of extinct amphibian and reptile species across the world. Frogs are of particular concern because an invasive fungus has recently caused many populations to collapse. The data are lists of specimens in museum collections. The method provides sensible results when the data are randomized or artificial extinctions are imposed. It suggests that about 200 frog extinctions have occurred and hundreds more will be lost over the next century, so we are on pace to create a mass extinction.There is broad concern that a mass extinction of amphibians and reptiles is now underway. Here I apply an extremely conservative Bayesian method to estimate the number of recent amphibian and squamate extinctions in nine important tropical and subtropical regions. The data stem from a combination of museum collection databases and published site surveys. The method computes an extinction probability for each species by considering its sighting frequency and last sighting date. It infers hardly any extinction when collection dates are randomized and it provides underestimates when artificial extinction events are imposed. The method also appears to be insensitive to trends in sampling; therefore, the counts it provides are absolute minimums. Extinctions or severe population crashes have accumulated steadily since the 1970s and 1980s, and at least 3.1% of frog species have already disappeared. Based on these data and this conservative method, the best estimate of the global grand total is roughly 200 extinctions. Consistent with previous results, frog losses are heavy in Latin America, which has been greatly affected by the pathogenic chytrid fungus Batrachochytrium dendrobatidis. Extinction rates are now four orders-of-magnitude higher than background, and at least another 6.9% of all frog species may be lost within the next century, even if there is no acceleration in the growth of environmental threats.
ER -